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Grade 12th passTrigonometry

Answer for the question in the image.its related to trigonometry

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Profile image of Swaroop shankar s
7 Years agoGrade 12th pass
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1 Answer

Profile image of Aditya Gupta
7 Years ago
we know that sin4A= 2sin2Acos2A
also, sin2A= 2t/(1+t^2) and cos2A= (1 – t^2)/(1+t^2), where t= tanA.
so, sin4A= 4t(1 – t^2)/(1+t^2)^2
but t= (a+root(1 – a))/(a+root(1+a))
substitute this value to get the final ans :)
further note that all the given options are wrong which can be verified by putting A= ½ and then checking all the options by a calculator.
kindly approve:)